1. Field of the Invention
This invention relates to the field of straining entrained solids from liquids, and more particularly to means and methods for passing the liquid material to be strained, under superatmospheric pressure, successively through a plurality of perforated drums having a corresponding number of media strainer inserts inserted within the perforations of the respective drums, whereby entrained solids are removed from the strained liquid by entrapment of the solids by the inserts. The invention is especially directed to such means and methods whereby, by creation of zones of reduced pressure along a dimension of each drum along which the inserts are disposed, and by rotating the drums, as the inserts pass through the reduced pressure zones, the higher pressure of liquid within the drums forces liquid through the inserts in the direction of reduced pressure and opposite the straining direction, thereby removing entrapped solids from the inserts and providing a automatic cleaning function.
2. Description of Related Art
The prior art includes strainers of the general type above described, but provided with a single perforated drum having media strainer inserts mounted within the drum perforations for straining solids contained in a liquid to be treated Such apparatus includes means and methods for automatic continuous self-cleaning by provision of a backwash slot and/or backwash shoe connected to atmosphere, thereby creating a zone of reduced pressure and whereby, on rotation of the drum, as the inserts pass through the reduced pressure zone established by the backwash mechanism, pressure inside the drum forces liquid outwardly of the drum, through the media strainer inserts, and removing entrapped solids therefrom such apparatus is manufactured by the assignee of the present invention.